So when we're playing a melody, we want to, sometimes, dress it up a little bit, and adding grace notes is a way to do that. A grace note is just a very small little passing tone, perhaps, might be a little rhythmic addition to what you're playing melodically.
So in the key of G, I might play something like. . .So that little grace note I threw in there is just a way to decorate something that already sounds good, but maybe you want to just add a little flourish. Here's another way you could use it. So a lot of it's hammer-ons, some of it's pull-offs. You might throw in a little slide.
It's just another, sort of, musical device that is at your disposal. You don't even have to know what a grace note is to play it, obviously. If you're inspired to throw any of this stuff in to make the melody more memorable, then you just do it. You don't have to know what the name of it is or what it's supposed to do. So keep at it. See you back here soon.